Concrete core for earth dams



Jan. 22, 1935. G. BOHRISCH CONCRETE CORE FOR EARTH DAMS Filed Aug. 19, 1953 J ve nfo/i Patented Jan. 22, 1935 CONCRETE coma. FOR EARTE DAMS I GotthardBohrisch, Mittweidmfiermany n Application August 19,

1933. sain uu.-ass,szr

In Germany October 26, 1932 6 Claims.

This invention relates to a concrete core for retaining earth dams.

Earth dams can be constructed by making use of unskilled labor to a very considerable extent, and this is particularly the case when earth dams with concrete core are raised. As the packing of the dam depends solely upon the concrete cores, the mere raising of the dam does not require such expert workmanship as do the usual building methods which operate with a clay apron or clay core.

Rigid concrete cores are known already, but they interfere with the reciprocal static effects of the dam masses facing the water and the air, which are due to considerable mutual motions in which the rigid concrete core does not participate. In order to employ the earth masses facing the air as supports and thus to produce earth resistance, it is necessary to construct the concrete core so as to be movable within. It has been proposed to divide the core into a large number of small concrete plates. Although this arrangement affords the advantage that the reciprocal static effects of the dam masses facing the air and the water are not disturbed, it is open to the objection that the packing of the dam, which depends solely upon the core, will be renderecl unsafe and expensive on account of the numerous joints involved.

There is also known already a type of dam in which only one horizontal joint is provided in the base of the core above the rock line forgiving the upper portion of the core an opportunity of becoming replaced relative to the base and even of tilting in said joint.

It has been found, however, that this construction is not satisfactory. Apart from the fact that the kind of joint chosen is unable to withstand larger motions without rendering the part of the dam concerned more or less pervious, horizontal displacement is very much limited in this joint, owing to great forces of friction.

It is further known to form the core substantially of three parts with horizontal joints between the various parts.

Compared with the known core constructions, the invention provides that the middle portion of a core consisting of three parts is constructed as a double hinge member corresponding to the length of the concrete core, so that safe packing is insured together with greatest mobility. All drawbacks connected with the former constructions are eliminated, and the construction itself is very simple. Preferably, the hinge member has longitudinal top and bottom clearances of semicircular cross section, which are engaged by the correspondingly rounded ends of the upper and lower core portions.

To reduce friction on the hinges as much as possible and to prevent it from disturbing the re- 5 ciprocal static effects of the mass of the dam, the cooperating hinge portions of the core have their contacting surfaces preferably covered with a material having a lower coeificient of friction than concrete while between the two parts of material a movable connection is provided to insure packing with respect to the length of the hinge. The surfaces of the longitudinal clearances may, for example, be covered with a slide sheet facing the upper and lower surface of the joint, and the movable connection between the upper and lower sheet may be formed by a looplike bend on the underwater side.

By way of example, the invention is illustrated in the accompanying drawing which shows one constructional embodiment of the invention and in which Figure 1 is a section of the concrete core and Fig. 2, a section of the hinges.

Referring to the drawing, the concrete core for the retaining earth dam comprises the top 1, the base 2 and the middle portion 3. Between the top 1 and the middle portion 3 as well as between the latter and the base 2 a hinge is formed by providing at each point a circular joint 4 of cylindrical shape and horizontal surface line. This circular joint 4 constitutes the working surface of the hinge. To reduce friction a metal sheet 5 is inserted in this joint 4 so as to be doubled up, as indicated in Fig. 2, the two parts of the sheet 5 sliding upon one another and are connected by the loop: 6 formed of the same material. Instead of sheet iron other materials can be used of course.

The double hinge member thus formed is located in the base of the entire core, and this 40 construction has practically no disturbing eifect upon the reciprocal static actions of the portions of the dam facing the water and the air, so that the core itself is exposed only to slight stresses and might be made less strong than 45 usual, which involves a considerable saving in concrete. The position of the hinges in the base of the core makes it further possible to prevent leakage through the hinges by arranging in front thereof a heavy layer of clay.

I claim:-

1. A concrete core for retaining earth dams, comprising a top, a base and a middle portion formed as double hinge member, said double hinge member possessing on top and bottom longitudinal clearances of semicircular cross section, said top and base having correspondingly rounded ends facing the middle portion and engaging the longitudinal clearances of the middle portion.

2. A concrete core according to claim 1, in which the surfaces of the longitudinal clearances have a covering consisting of a material having a lower coeflicient of friction than concrete.

3. A concrete core according to claim 1, in which the surfaces of the longitudinal clearances have a covering consisting of a material having a lower coefficient of friction than concrete, and in which a movable water-excluding connection is provided between the two coverings in the length of the core.

4. A concrete core according to claim 1, in

which the surfaces of the longitudinal clearances are covered with a folded piece of sheet metal possessing a looplike bend on the underwater side of the core.

5. A concrete core for retaining earth dams, comprising three superposed parts packed relative to one another, the central portion of said core forming a hinge with the upper part and a second hinge with the base, both hinges having the length of the dam.

6. A concrete core for retaining earth dams, comprising three portions, a top, a middle portion and a base, the said middle portion of the core forming a hinge of cylindrical shape with the top portion, and a second hinge of cylindrical shape with the base, the said hinges having the length of the dam.

GOTTI-IARD BOHRISCH. 

